The parent applications disclose simple PIR motion sensors with low false alarm rates and minimal processing requirements that are capable of discriminating smaller moving targets, e.g., animals, from larger targets such as humans, so that an alarm will be activated only in the presence of unauthorized humans, not pets.
In U.S. Pat. No. 5,923,250, incorporated herein by reference, a motion sensing system is disclosed that uses dead zones between monitored volumes of a space for reducing false alarms caused by small animals. A moving object is indicated not by simultaneous differences in signals between detectors (such as different frequencies), but simply by noting that the detectors alternatingly produce a temporal sequence of signals as the object moves through the volumes. The present invention recognizes that the principles of the parent applications can be applied with inventive modification to the system disclosed in the '250 patent to obviate the need for dead zones while maintaining functionality.